The rivalry between Sunni and Shia Muslims has lasted more than 1,400 years
Tensions between both branches of Islam have been rife for thousands of years, with both vying to be the dominant nation in the Middle East.
Saudi Arabia – dubbed the Sunni kingdom – is ruled by a Sunni monarchy, with 90 per cent of its population adopting the same faith.
But 95 per cent of the Islamic Public of Iran belongs to the Shia branch.
Here is everything you need to know about both Islamic sects.
How do Sunni and Shia differ?
The Sunni and Shia sects agree on many aspects of Islam, however there are also large disagreements between both sides.
Shias look towards the rewards of the afterlife and value the celebration of martyrdom.
Shias – also known as Twelvers – consider Ali and the leaders who came after him as Immams.
Many believe in a line of 12 Imams, the last of which was a boy believed to have vanished in the ninth century in Iraq after his father was murdered – and they expect his return as the Messiah.
However Sunnis emphasise God’s power in the material world – including the public and political realm.
Salman bin Abdulaziz Al Saud currently leads the House of Saud which rules Saudi Arabia
What caused the divide between Sunni and Shia?
The 1,400 year split between both sects dates back immediately after the Prophet Mohammed’s death in 632.
Mohammed died without appointing a successor, leading to a split over the religion over whether its next leader should be chosen democratically or whether the Prophet’s blood relatives should reign.
The Sunnis believed Mohammed’s friend and advisor Abu Bakr was the rightful “caliph” of Muslims, while Shias thought that his cousin and son-in-law Ali was chosen by Allah to rule.
Abu Bakr held the title first until his death, while Ali was crowned caliph fourth after two previous rulers were assassinated.
But the split became more severe between Sunnis and Shias when trying decide over who came next.
Sunni Muslims argue their interpretation of Islam follows the ways of Mohammed (the Sunnah), Shias claim Ali was the rightful first caliph and only his descendants could claim to be the true leaders of Muslims.
Both sides claim to be the one “pure” branch of Islam.
The Shia Ayatollah Ali Khamenei, the head of state of the Islamic Republic of Iran
Are Sunnis or Shias a larger group or Muslim?
The majority of Muslims across the world are Sunni – making up almost 85 per cent of Islam’s followers, while Shia Muslims remain confined to the Middle East.
Where can Sunni and Shia Muslims be found?
Sunni Muslims are spread throughout the world and make up the dominant religion in North Africa and the Middle East.
Shia Muslims on the other hand hold a majority in Iran, Iraq, Azerbaijan and Bahrain – but there are also significant Shia populations in Yemen, Lebanon, Kuwait, Syria and Qatar.
Despite being members of the religious minority, the Saudi-backed Bahrain has long been ruled by the Sunni House of Khalifa.
Meanwhile, Iraq was ruled by Saddam Hussein – who was a Sunni Muslim – for more than 20 years, during which he savagely pressed Shia Muslims.
Iraq, which is predominantly Shia, was ruled by Sunni Muslim Saddam Hussein for more than 20 years